Nanostructured TiO₂-based gas sensors with enhanced sensitivity to reducing gases

• Wojciech Maziarz,
• Anna Kusior and
• Anita Trenczek-Zajac

Beilstein J. Nanotechnol. 2016, 7, 1718–1726, doi:10.3762/bjnano.7.164

• deposition [24][25], and thermal, chemical, and electrochemical (anodization) oxidation [26][27][28][29]. Thermal and chemical oxidation seem to be the easiest to perform, the least expensive, and have interlaboratory reproducibility as an additional advantage. TiO2 is obtained mainly in form of thin film

Properties of Ni and Ni–Fe nanowires electrochemically deposited into a porous alumina template

• Alla I. Vorobjova,
• Dmitry L. Shimanovich,
• Kazimir I. Yanushkevich,
• Sergej L. Prischepa and
• Elena A. Outkina

Beilstein J. Nanotechnol. 2016, 7, 1709–1717, doi:10.3762/bjnano.7.163

• anodization of Al foil, as described in details elsewhere [35]. First, commercial aluminium foil (99.995%) with a size of 60 × 48 mm and a thickness of ca. 100 µm is annealed at 350 °C for 1 h. Then, the samples were electropolished in a mixture of chloric acid and acetic acid 1:4 (volumetric ratio) at T ≈ 8

• °C and a voltage of 25 ± 2 V for 1–2 min to reduce the surface roughness. Next, the samples were washed in distilled water and dried in a dry air stream. Before anodization, the technological frame has been formed along the perimeter and in the center of the substrate. It is necessary to strengthen

• the mechanical stability of a free-standing membrane and to restrict certain zones with identical surface area. The frame destination and its formation procedure are described in more detail in [35]. Thick porous alumina films with ordered structure of pores have been prepared by two-step anodization

A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors

• Vardan Galstyan,
• Elisabetta Comini,
• Iskandar Kholmanov,
• Andrea Ponzoni,
• Veronica Sberveglieri,
• Nicola Poli,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2016, 7, 1421–1427, doi:10.3762/bjnano.7.133

• (C2H2O4·2H2O) containing ethanol using a two-electrode system. A platinum foil was used as a counter electrode and the anodization process was carried out at room temperature. The obtained structures were zinc oxalate dihydrate (ZnC2O4·2H2O). The as-prepared samples were transformed to crystalline ZnO by

Fast diffusion of silver in TiO₂ nanotube arrays

• Wanggang Zhang,
• Yiming Liu,
• Diaoyu Zhou,
• Hui Wang,
• Wei Liang and
• Fuqian Yang

Beilstein J. Nanotechnol. 2016, 7, 1129–1140, doi:10.3762/bjnano.7.105

• schematically illustrated in Figure 1. The pure TiO2 nanotubes are prepared by a simple two-step anodization process, and then a layer of Ag film is deposited on the top of the TiO2 nanotubes via sputtering magnetron. The heat treatment of the TiO2 nanotubes with Ag nanofilm leads to the formation of Ag@TiO2

• nanotubes. Figure 2 shows typical SEM images of the pure TiO2 nanotube arrays prepared by a two-step anodization process without heat treatment. It is evident that the prepared pure TiO2 nanotube arrays consist of regular tubes with a diameter of 75 ± 5 nm, a wall thickness of 7 ± 2 nm and an average length

• of about 6.5 μm. The outmost surface of the pure TiO2 nanotubes prepared by the two-step anodization process is relatively clean and smooth, as shown in Figure 2b. For comparison, typical SEM images of the pure TiO2 nanotube arrays prepared by a one-step anodization process are shown in Figure S1c in

Large-scale fabrication of achiral plasmonic metamaterials with giant chiroptical response

• Morten Slyngborg,
• Yao-Chung Tsao and
• Peter Fojan

Beilstein J. Nanotechnol. 2016, 7, 914–925, doi:10.3762/bjnano.7.83

• to fabricate functionalized surfaces applicable for sensors with increased sensitivity or arrays hereof in a cheap and scaleable way. Experimental Fabrication of extrinsic chiral metamaterials The original molds were prepared by anodic aluminum oxidation using a custom-built anodization and wet

• nm. The substrate with 300 nm interpore distance was prepared by anodization in 0.3 M oxalic acid solution at 140 V and with a solution temperature of 283 ± 0.5 K for 40 min. The substrate with 430 nm interpore distance was prepared by anodization in 1 M phosphoric acid solution at 180 V and with a

• solution temperature of 273 ± 0.5 K for 100 min. The substrate with 600 nm interpore distance was prepared by anodization in 2 M citric acid solution at 285 V and with a solution temperature of 293 ± 0.5 K for 20 min. More details on the fabrication of the original mold has been reported previously [39

Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method

• Mikalai V. Malashchonak,
• Alexander V. Mazanik,
• Olga V. Korolik,
• Еugene А. Streltsov and
• Anatoly I. Kulak

Beilstein J. Nanotechnol. 2015, 6, 2252–2262, doi:10.3762/bjnano.6.231

• . The synthesis of the titanium dioxide nanotube arrays was carried out in a two-electrode electrochemical cell by anodization of metallic titanium with a graphite counter electrode in an aqueous electrolyte containing 1 mol/L (NH4)2SO4, 0.1 mol/L NH4F and 0.2 mol/L H2C2O4 with pH 2.8 (corrected with

• NaOH) under the electrode potential bias of 25 V for 20 h at room temperature [37]. The rate of potential bias sweep from 0 to 25 V at the initial stage was 250 mV/s. After anodization, the electrodes were immediately immersed into a 1.2 mol/L (NH4)2SO4 solution for 24 h then rinsed with distilled

Electrochemical coating of dental implants with anodic porous titania for enhanced osteointegration

• Amirreza Shayganpour,
• Alberto Rebaudi,
• Pierpaolo Cortella,
• Alberto Diaspro and
• Marco Salerno

Beilstein J. Nanotechnol. 2015, 6, 2183–2192, doi:10.3762/bjnano.6.224

• , following the success of nanostructured anodic porous alumina, anodic porous titania has also attracted the interest of academic researchers. This material, investigated mainly for its photocatalytic properties and for applications in solar cells, is usually obtained from the anodization of ultrapure

• the anodization in the presence of electrolyte additives such as magnesium, these can be incorporated into the porous coating. The proposed method for the surface nanostructuring of biomedical implants should allow for integration of conventional microscale treatments such as sandblasting with

• additive nanoscale patterning. Additional advantages are provided by this material when considering the possible loading of bioactive drugs in the porous cavities. Keywords: anodization; dental implants; nanopores; surface treatment; titania; Introduction Titanium (Ti) is the standard material used for

Nanomechanical humidity detection through porous alumina cantilevers

• Olga Boytsova,
• Alexey Klimenko,
• Vasiliy Lebedev,
• Alexey Lukashin and
• Andrey Eliseev

Beilstein J. Nanotechnol. 2015, 6, 1332–1337, doi:10.3762/bjnano.6.137

• Preparation of the cantilever array AAO layer formation was carried out in 0.3 M H2C2O4 (98%, Aldrich) at a constant voltage of 40 V. The electrolyte was pumped through the two-electrode cell by a peristaltic pump, and its temperature was kept constant (2 °C) during anodization. The films with a thickness of

• equals 800 × 100 × 2 µm3 (Figure 5). One should note that these dimensional characteristics can be simply tuned by choosing lithographical mask with the desired cantilever shapes and varying of anodization charge. Films were characterized by optical (Nikon Eclipse 600pol) and scanning electron (LEO Supra

Nanoporous Ge thin film production combining Ge sputtering and dopant implantation

• Jacques Perrin Toinin,
• Alain Portavoce,
• Khalid Hoummada,
• Michaël Texier,
• Maxime Bertoglio,
• Sandrine Bernardini,
• Marco Abbarchi and
• Lee Chow

Beilstein J. Nanotechnol. 2015, 6, 336–342, doi:10.3762/bjnano.6.32

• is compatible with complementary metal oxide semiconductor (CMOS) technology, the production of porous Ge thin films could be used for integration of optoelectronic devices in Si microelectronic technology. The production of porous Ge can be performed using several techniques such as anodization and

Optical modeling-assisted characterization of dye-sensitized solar cells using TiO₂ nanotube arrays as photoanodes

• Jung-Ho Yun,
• Il Ku Kim,
• Yun Hau Ng,
• Lianzhou Wang and
• Rose Amal

Beilstein J. Nanotechnol. 2014, 5, 895–902, doi:10.3762/bjnano.5.102

• fabricating DSSCs, the anodization condition for TNT arrays as photoelectrodes was determined. The lengths of TNT arrays employed in the DSSCs fabrication were 3.3, 11.5, and 20.6 μm with different pore diameters of 50, 78.6, and 98.7 nm, respectively. In Figure 1, TNT-based DSSCs are operated by harvesting

• modeling contributes to a deeper understanding of the improved light harvesting and charge transport properties observed in the solar cell devices using 1D-TNT photoanodes. Experimental Fabrication of TNT-based DSSCs Under the anodization conditions of 60 V with ethylene glycol containing 0.5 wt % NaF and

• illumination (Inset SEM image indicates well-ordered TNT arrays prepared by anodization). Photocurrent–voltage characteristics of N719-DSSCs fabricated by using 3.3 μm, 11.5 μm, and 20.6 μm TNT arrays under an AM 1.5 solar simulator (100 mW·cm−2). IPCE spectrum of the N719-DSSCs fabricated by using 3.3 μm

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

• Hongjun Chen and
• Lianzhou Wang

Beilstein J. Nanotechnol. 2014, 5, 696–710, doi:10.3762/bjnano.5.82

• spectra between transition metal oxides and gold nanoparticles. Due to N-doping and N- and F-impurities generated in the anodization process, the N-doped TiO2 nanoparticles and TiO2 nanotubes have absorption spectra in the visible range and show an overlap with that of gold nanoparticles. Therefore, when

A visible-light-driven composite photocatalyst of TiO₂ nanotube arrays and graphene quantum dots

• Donald K. L. Chan,
• Po Ling Cheung and
• Jimmy C. Yu

Beilstein J. Nanotechnol. 2014, 5, 689–695, doi:10.3762/bjnano.5.81

• anodization. A subsequent annealing at 450 °C resulted in the formation of N 2p states above the valence band of TiO2 and hence in a red shift of the absorption edge [41]. The absorption spectrum of amine-functionalized TNAs is similar to that of pristine TNAs. For GQDs/TNAs, higher absorption intensity at

• % deionized (DI) water was used as electrolyte. Ti foil (2 cm × 3 cm) was used as a working electrode, and a Pt foil (1 cm × 1 cm) served as a counter electrode. Prior to anodization, Ti foils were washed with ethanol, acetone by ultrasonication to remove contaminants, subsequently rinsed with DI water and

• dried in air. At room temperature, anodization is carried out by immersing a Ti foil in as-prepared electrolyte for 3 h at 60 V. Afterwards, the sample was removed from the electrochemical cell, rinsed with DI water, sonicated in ethanol for 2 min to remove surface debris. A subsequent heating to 450 °C

3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid

• Loïc Assaud,
• Evans Monyoncho,
• Kristina Pitzschel,
• Anis Allagui,
• Matthieu Petit,
• Margrit Hanbücken,
• Elena A. Baranova and
• Lionel Santinacci

Beilstein J. Nanotechnol. 2014, 5, 162–172, doi:10.3762/bjnano.5.16

• aluminum oxide (AAO) has been used as nanostructured support for the Pd catalysts. The AAO membranes are attractive because they exhibit a high specific surface area and the pore diameter and length can be tailored easily [27][28]. In this study, the usual two-step anodization process shown in Figure 1a–e

• H2CrO4 and H3PO4 at 50 °C for 12 h. The second anodization step is then carried out during 2.5 h at the same anodic conditions. Pd-catalyzed electrooxidation of HCOOH on Pd surfaces. Supporting Information Supporting Information File 36: Additional experimental details Acknowledgements The authors

Preparation of electrochemically active silicon nanotubes in highly ordered arrays

• Tobias Grünzel,
• Young Joo Lee,
• Karsten Kuepper and
• Julien Bachmann

Beilstein J. Nanotechnol. 2013, 4, 655–664, doi:10.3762/bjnano.4.73

• matrix (white) will be prepared by the two-step anodization of aluminum, a procedure which enables the experimentalist to generate templates of ordered cylindrical pores with a tunable period 50 nm ≤ P ≤ 450 nm and a length 0.1 µm ≤ L ≤ 100 µm [10][11]. Subsequently, the functional material will be

• preparation The preparative path devised for making ordered arrays of electrically contacted silicon nanotubes is presented in Figure 2. In the first step (a), a double anodization (electrochemical oxidation of aluminum in a protic solution) is carried out under 40 V in oxalic acid at 7 °C according to the

• standard procedure [11]: after the first anodization, the disordered porous aluminum oxide layer obtained is removed in chromic acid, then the ordered porous layer is obtained by a second anodization in the same conditions. The length of the pores is defined by the duration of this second anodization

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes

• Thomas Baumgärtel,
• Christian von Borczyskowski and
• Harald Graaf

Beilstein J. Nanotechnol. 2013, 4, 218–226, doi:10.3762/bjnano.4.22

• functionalization of silicon oxide nanostructures prepared by AFM-anodization lithography of alkyl-terminated silicon. Different conditions for the growth of covalently bound mono-, multi- or submonolayers of distinctively functional silane molecules on nanostructures have been identified by AFM-height

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• -covered micropores exemplified in Figure 10 and Figure 11 [3][7][13]. The PS interface is generated by electrochemical anodization of 1–20 Ω·cm, n-type (phosphorous-doped) silicon(100) wafers (Wafer World) or 7–13 Ω·cm (Figure 10), p-type (boron-doped) silicon(100) wafers (Siltronix) (Figure 11). The

• anodization of the n-type wafers [31][32] is done under topside illumination by using a Blak-Ray mercury lamp. The silicon wafer is etched in a 1:1 solution of HF and ethanol at a current between 8–15 mA/cm [27][28][32][33]. The anodized n-type sample is placed in methanol for a short period and subsequently

• × 5 mm are opened in this layer by Reactive Ion Etching (RIE). The SiC layer serves two purposes: SiC makes it possible to form the hybrid micro/nanoporous PS structure in the 2 × 5 mm windows during electrochemical anodization because of its resistance to HF. The SiC also aids the placement of gold

Macromolecular shape and interactions in layer-by-layer assemblies within cylindrical nanopores

• Thomas D. Lazzara,
• K. H. Aaron Lau,
• Wolfgang Knoll,
• Andreas Janshoff and
• Claudia Steinem

Beilstein J. Nanotechnol. 2012, 3, 475–484, doi:10.3762/bjnano.3.54

• . Results and Discussion For our studies on LbL deposition of globular proteins and linear-PE multilayers, we used the nanopores of anodic aluminum oxide (AAO). Scheme 1 (top) shows the general expected internal structure after LbL deposition in AAO nanopores. A two-step anodization process of the AAO

• , according to a previously reported technique [49]. Briefly, AAO membrane thin films were fabricated by electrochemical anodization of aluminum foils after electrochemical polishing. Polished aluminum foils were anodized for 2 h in 0.3 M oxalic acid, 1 °C at 40 V. The alumina was removed with H3PO4 (5 vol

Self-assembled monolayers and titanium dioxide: From surface patterning to potential applications

• Yaron Paz

Beilstein J. Nanotechnol. 2011, 2, 845–861, doi:10.3762/bjnano.2.94

• anodization of titanium in HF. Here, SAMs of 1H,1H,2H,2H-perfluorooctyl-triethoxysilane were chemisorbed on selected areas in the nanotube array and served to selectively protect the nanotubes upon immersion in HF [84]. Electron transfer in SAMs connected to TiO2 Electron transfer through SAMs has been

Microfluidic anodization of aluminum films for the fabrication of nanoporous lipid bilayer support structures

• Jaydeep Bhattacharya,
• Alexandre Kisner,
• Andreas Offenhäusser and
• Bernhard Wolfrum

Beilstein J. Nanotechnol. 2011, 2, 104–109, doi:10.3762/bjnano.2.12

• monitored by impedance spectroscopy across the nanoporous alumina membrane in real-time. Our approach offers a simple and efficient methodology to investigate the activity of transmembrane proteins or ion diffusion across membrane bilayers. Keywords: anodization; lipid bilayer; microfluidics

• formation of lipid bilayers on top of the nanoporous membrane which is monitored using impedance spectroscopy. Experimental The experimental setup for the microfluidic anodization approach is shown schematically in Figure 1. The aluminum substrate, either a 30 µm thick aluminum foil or a thin aluminum film

• the anodization was indicated by a steep drop in the anodization current indicating the formation of a residual alumina barrier layer. Oxalic acid was then rinsed from the channel and 5% phosphoric acid injected into the upper and lower channels to remove the remaining alumina film at the bottom of